Fukushima Daiichi NPS Prompt Report (Sep 04, 2013)Detailed Analysis Results on Groundwater around Units 1 to 4 at Fukushima Daiichi NPS
We conducted a purification test of wells (sub-drain pits) located next to the Units 1-4 buildings at Fukushima Daiichi NPS, and detected radioactive materials in water accumulated in the pits. One possible cause of the entrance of radioactive materials there is fallout. In order to find out the influence of fallout, we are planning to install new observation wells around the Units 1-4 buildings.
We sampled water from the newly installed sub-drain observation well 2R-1 at the side of Unit 2 Reactor Building (on the mountain facing side) yesterday (on September 3). We would like to announce measurement results for radioactive materials such as cesium and all β as we obtained the results today (on September 4).
As a result of the measurement, the all β and cesium-137 densities were found to be about 10 times higher than those in the groundwater bypass pump wells, which are located nearer to the mountains than this observation well. However, since these densities are sufficiently low compared to those in the nearby sub-drains, we assume that fallout affected the results obtained this time.
The tritium density was at the same level as the densities in the groundwater bypass pump wells.
<Sub-drain observation well 2R-1>
- Sampling on September 3
Cesium-134 ND: (0.55Bq/L) [Density limit by the announcement of reactor regulation: 60Bq/L]
Cesium-137: 0.97Bq/L [Density limit by the announcement of reactor regulation: 90Bq/L]
All β: 36Bq/L
Tritium: 31Bq/L [Density limit by the announcement of reactor regulation: 60,000Bq/L]
* ND indicates a case where the result was below the detection limit value. The detection limit value is shown in the parentheses.
We will continue to monitor the densities by conducting sampling and analysis.
For the past sampling results, please refer to the following page on our website:
http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/index-e.html
